Pneumatically powered pole saw

ABSTRACT

A pneumatic valve assembly with a trigger for switching the pneumatic valve assembly between two or more valve operation modes is disclosed herein. The valve operational modes are determined by selection of fluid conduits by a trigger valve assembly of the pneumatic valve assembly which interconnects fluid conduits to a main valve, pilot valves and a pneumatic cylinder of a fluid powered pole saw and wherein a piston located in the pneumatic cylinder is mechanically coupled to a cutting blade of the pole saw and the trigger is operatively coupled to the trigger valve assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. patent applicationSer. No. 13/448,340 filed Apr. 16, 2012, which is a continuation in partof U.S. patent application Ser. No. 12/265,795 filed Nov. 6, 2008 nowU.S. Pat. No. 8,156,665, which claims the benefit of U.S. ProvisionalPatent Application Ser. No. 60/986,865 filed Nov. 9, 2007, the contentseach of which are incorporated herein by reference thereto.

This application is also a continuation in part of U.S. patentapplication Ser. No. 14/250,152 filed Apr. 10, 2014, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/810,440 filedApr. 10, 2013, the contents each of which are incorporated herein byreference thereto.

This application is also a continuation in part of U.S. patentapplication Ser. No. 14/394,738 filed Apr. 15, 2013, which is a NationalStage Entry of PCT/US2013/036564, which claims priority to U.S. patentapplication Ser. No. 13/448,340 filed Apr. 16, 2012 and U.S. ProvisionalPatent Application Ser. No. 61/810,440 filed Apr. 10, 2013, the contentseach of which are incorporated herein by reference thereto.

BACKGROUND

Various embodiments of the present invention relate to a pneumaticallypowered pole saw.

Manually operated pole saws require an operator to manually push andpull a long pole back and forth in order to move a saw blade attached tothe end of the pole, thereby cutting tree limbs with the attached sawblade. These pole saws rely entirely upon the operator force thenecessary forces to be applied to the cutting blade or saw blade of thepole saw. Accordingly, and as the operator tires the efficiency of thecutting operation is reduced.

Accordingly, it is desirable to provide a powered pole saw having ameans for efficiently converting stored energy into kinetic energywherein the saw blade of the pole saw is actuated.

SUMMARY OF THE INVENTION

A pneumatically powered pole saw and method of operating is provided.Exemplary embodiments are directed to a pneumatically powered pole saw,comprising: an extendable pole; a head member secured to the extendablepole; a cutting blade movably mounted to the head member; a pistonlinked to the cutting blade, the piston being slidably received within apiston chamber of the head member; a reciprocating valve disposed in thehead member, the reciprocating valve being configured for movementbetween a first position and a second position wherein the reciprocatingvalve releases a portion of a source of compressed gas into the pistonchamber on one side of the piston when the reciprocating valve is in thefirst position causing the cutting blade to move in a first cuttingdirection towards a limit of travel in the first cutting direction and afirst check valve provides fluid communication to the piston chamber onanother side of the piston causing the reciprocating valve to move fromthe first position towards the second position, when the cutting bladereaches the limit of travel in the first direction, the reciprocatingvalve releases another portion of the source of compressed gas into thepiston chamber on the another side of the piston when the reciprocatingvalve is in the second position causing the cutting blade to move in asecond cutting direction opposite to the first cutting direction andtowards a limit of travel in the second cutting direction and a secondcheck valve provides fluid communication to the piston chamber on theone side of the piston, the reciprocating valve moving from the secondposition towards the first position when the cutting blade reaches alimit of travel in the second direction.

In another embodiment, a pneumatically powered pole saw is provided, thepole saw having: a pole; a cutting blade movably mounted to the pole; apiston slidably received within a piston chamber of the pole; a pistonrod coupling to the cutting blade to the piston; gas actuated mainvalves configured for movement between first positions and secondpositions wherein the gas actuated main valves are located in a mainvalves assembly fluidly coupled to the piston chamber; a first pilotvalve configured to send actuating gas through a conduit to the mainvalves assembly, the actuating gas of the first pilot valve actuatingthe gas actuated valves of the main valves assembly to the firstposition, wherein movement of the main valves to the first positionreleases a portion of a source of gas into the piston chamber on oneside of the piston while venting the opposite side of the pistonchamber, and when the main valves assembly is in the first position thecutting blade to moves in a first cutting direction towards a limit oftravel in the first cutting direction; a second pilot valve configuredto send actuating gas through a conduit to the main valves assembly whenthe limit of travel in the first cutting direction has been reached, theactuating gas of the second pilot valve causes the main valves to bemoved to the second position, wherein movement of the main valves to thesecond position releases another portion of compressed gas into thepiston chamber on the opposite side of the piston chamber and ventingthe one side of the piston chamber, wherein the cutting blade moves inan opposite second cutting direction with respect to the first cuttingdirection until a limit of travel in the second cutting direction isreached wherein the first pilot valve is again actuated and the cuttingblade moves again in the first cutting direction until the limit oftravel in the first cutting direction is reached.

In yet another embodiment, a pneumatically powered pole saw is provided,the pneumatically powered pole saw having: a pole; a cutting blademovably mounted to the pole; a piston slidably received within a pistonchamber of the pole; a piston rod coupling to the cutting blade to thepiston; gas actuated main valves configured for movement between firstpositions and second positions wherein the gas actuated main valves arelocated in a main valves assembly fluidly coupled to the piston chamber;a first pilot valve configured to send actuating gas through a conduitto the main valves assembly, the actuating gas of the first pilot valveactuating the gas actuated valves of the main valves assembly to thefirst position, wherein movement of the main valves to the firstposition releases a portion of a source of gas into the piston chamberon one side of the piston while venting the opposite side of the pistonchamber, and when the main valves assembly is in the first position thecutting blade to moves in a first cutting direction towards a limit oftravel in the first cutting direction; and a second pilot valveconfigured to send actuating gas through a conduit to the main valvesassembly when the limit of travel in the first cutting direction hasbeen reached, the actuating gas of the second pilot valve causes themain valves to be moved to the second position, wherein movement of themain valves to the second position releases another portion ofcompressed gas into the piston chamber on the opposite side of thepiston chamber and venting the one side of the piston chamber, whereinthe cutting blade moves in an opposite second cutting direction withrespect to the first cutting direction until a limit of travel in thesecond cutting direction is reached wherein the first pilot valve isagain actuated and the cutting blade moves again in the first cuttingdirection until the limit of travel in the first cutting direction isreached.

In another embodiment, a pneumatic valve assembly is provided, thepneumatic valve assembly having: a piston slidably received within apiston chamber a piston rod coupled to the piston; gas actuated mainvalves configured for movement between first positions and secondpositions wherein the gas actuated main valves are located in a mainvalves assembly fluidly coupled to the piston chamber; a first pilotvalve configured to send actuating gas through a conduit to the mainvalves assembly, the actuating gas of the first pilot valve actuatingthe gas actuated valves of the main valves assembly to the firstposition, wherein movement of the main valves to the first positionreleases a portion of a source of gas into the piston chamber on oneside of the piston while venting the opposite side of the pistonchamber, and when the main valves assembly is in the first position thepiston rod moves in a first direction towards a limit of travel in thefirst direction; a second pilot valve configured to send actuating gasthrough a conduit to the main valves assembly when the limit of travelin the first direction has been reached, the actuating gas of the secondpilot valve causes the main valves to be moved to the second position,wherein movement of the main valves to the second position releasesanother portion of compressed gas into the piston chamber on theopposite side of the piston chamber and venting the one side of thepiston chamber, wherein the piston rod moves in an opposite seconddirection with respect to the first direction until a limit of travel inthe second direction is reached wherein the first pilot valve is againactuated and the piston rod moves again in the first direction until thelimit of travel in the first direction is reached; and wherein the mainvalves assembly, the first pilot valve and the second pilot valve areeach configured to slidably receive the piston rod therein.

In yet another embodiment, a method for pneumatically powering a polesaw is provided, the method including the steps of: slidably mounting apiston in a piston chamber for movement between a first position and asecond position; and moving a reciprocating valve fluidly coupled to thepiston chamber, wherein the reciprocating valve is configured formovement between a first position and a second position wherein thereciprocating valve releases a portion of a source of compressed gasinto the piston chamber on one side of the piston when the reciprocatingvalve is in the first position causing the piston to move in a firstdirection towards a limit of travel in the first direction and a firstcheck valve provides fluid communication to the piston chamber onanother side of the piston causing the reciprocating valve to move fromthe first position towards the second position, when the piston reachesthe limit of travel in the first direction, the reciprocating valvereleases another portion of the source of compressed gas into the pistonchamber on the another side of the piston when the reciprocating valveis in the second position causing the piston to move in a seconddirection opposite to the first cutting direction and towards a limit oftravel in the second direction and a second check valve provides fluidcommunication to the piston chamber on the one side of the piston, thereciprocating valve moving from the second position towards the firstposition when the piston reaches a limit of travel in the seconddirection, wherein movement of the piston between the limits of travelin the first and second directions causes the reciprocating valve tomove between the first position and the second position.

In still another embodiment, a compressed gas switching pneumatic valveassembly is provided, the valve assembly having: an outer pneumaticchamber; and a slidably received gas sealed valve member within theouter pneumatic chamber, wherein an internal void extends from one sideof the outer pneumatic chamber to another side of the outer pneumaticchamber, the internal void being configured to allow axial location ofan pneumatic valve assembly around an axially located piston rod of apneumatic piston chamber, the pneumatic valve assembly furthercomprising at least fluid paths to provide switchable fluid flow intoand out of the outer pneumatic chamber when the slidably received valvemember is externally actuated to change a position within the outerpneumatic chamber.

In another embodiment, a pneumatic valve assembly is provided. Thepneumatic valve assembly having a trigger for switching the pneumaticvalve assembly between two or more valve operation modes, the valveoperational modes are determined by selection of fluid conduits by atrigger valve assembly of the pneumatic valve assembly whichinterconnects fluid conduits to a main valve, pilot valves and apneumatic cylinder of a fluid powered pole saw and wherein a pistonlocated in the pneumatic cylinder is mechanically coupled to a cuttingblade of the pole saw and the trigger is operatively coupled to thetrigger valve assembly.

In another embodiment, a method of manually triggering a configurationof valves between pneumatic pilot valves and main valves which controlthe flow of compressed fluid to a pneumatic cylinder of a pneumaticallypowered pole saw is provided. The method comprising the steps of:actuating a trigger valve assembly via a trigger such that apneumatically driven blade of the pole saw is held in a fully extendedposition with respect to the pole saw when reciprocating motion of thepole saw piston is deactivated; and biasing a shuttle of the pole saw toa position corresponding to the fully extended position of the bladewhen the shuttle is not in the position when reciprocating motion of thepole saw piston is deactivated.

In another embodiment, a pneumatically powered pole saw is provided. Thepole saw having: a pole; a cutting blade movably mounted to the pole; apiston slidably received within a piston chamber of the pole; a pistonrod coupling to the cutting blade to the piston; and a pneumatic valveassembly with a trigger for switching between two or more valveoperation modes, the valve operational modes are determined by selectionof fluid conduits by a trigger valve assembly which interconnects fluidconduits to a main valve, pilot valves and a pneumatic cylinder of thepole saw and wherein valves of the trigger valve assembly are configuredto provide a static state, held to one extreme position of the pistonwherein the cutting blade is held in a fully extended position withrespect to the pole saw.

The above-described and other features are appreciated and understood bythose skilled in the art from the following detailed description,drawings, and appended claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pneumatically powered pole sawconstructed in accordance with an exemplary embodiment of the presentinvention;

FIG. 1A is a perspective view of a pneumatically powered pole sawconstructed in accordance with an alternative exemplary embodiment ofthe present invention;

FIGS. 1B-D illustrate saw blades for use in various exemplaryembodiments of the present invention;

FIG. 2 is a side view of a pneumatically powered pole saw constructed inaccordance with an exemplary embodiment of the present invention;

FIG. 3 is a view along lines 3-3 of FIG. 2;

FIG. 4 is a cross-sectional view along lines 4-4 of FIG. 3;

FIGS. 5A-5D are schematic illustrations of exemplary embodiments of thepresent invention;

FIG. 6 is a view illustrating one exemplary embodiment of the presentinvention;

FIG. 7 is a view illustrating another exemplary embodiment of thepresent invention;

FIG. 8 is a view illustrating an exemplary embodiment of the presentinvention;

FIGS. 9A-9B are schematic illustrations of alternative embodiments ofthe present invention;

FIGS. 10A-10B are enlarged views of a reciprocating valve shown in FIGS.9A-9B;

FIGS. 11A-11B are enlarged views showing operational positions of thecheck valves shown in FIGS. 9A-9B; and

FIGS. 12A-19C illustrate various view of alternative exemplaryembodiments of the present invention.

FIG. 20 illustrates primary pneumatic subassemblies according to analternative embodiment without their pneumatic inter-connections;

FIG. 21A is a view along lines 21A-21A of FIG. 20 illustratingcomponents within each of the subassemblies as well as the conduitsinterconnecting these subassemblies;

FIGS. 21B and 21C illustrate the same cut-away view as FIG. 21A,however, each shows a different operational state for the internalcomponents. The operational states are described in the associated textof the present application; and

FIGS. 22-28 illustrate various embodiments of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In accordance with exemplary embodiments of the present invention, apneumatically powered pole saw and method for operating the pole saw isdisclosed. In an exemplary embodiment the pneumatically powered pole sawwill comprise a source of compressed gas for use in driving the blade ofthe pole saw.

Referring now to FIGS. 1-5, a pneumatically powered pole saw 10constructed in accordance with an exemplary embodiment of the presentinvention is illustrated. Pneumatically powered pole saw 10 has acutting blade 12 movably mounted to a head member 14 of thepneumatically powered pole saw. Head member 14 further comprises acylinder 16 configured to sildably receive a piston 18 therein. Inaccordance with an exemplary embodiment of the present invention piston18 has at least one O-ring or sealing member that allows the piston toslide within the cylinder while also preventing or limiting fluidcommunication therethrough (e.g., maintaining or preventing fluids orgases on one side of the piston from passing around the piston toanother side of the piston). Piston 18 is secured to a rod 20 that issecured to cutting blade 12 via a mount 22. Rod 20 passes through asealed end of the housing wherein the rod is allowed to slide in and outwithout the release of the gases in the chamber through the opening therod slides in. Mount 22 is configured to removably secure the cuttingblade to the mount thus allowing removal and replacement of the cuttingblade as it becomes worn, damaged or dulled. In one exemplaryembodiment, the mount 22 has a pair of rollers 24 slidably receivedwithin a pair of complimentary channels or slots 26 disposed in a frameportion 28 of the head member. Rollers 24 allow the mount and thecutting blade to slide within a range of movement on the head member.

In one non-limiting exemplary embodiment, the head member furthercomprises a roller 30 rotatably mounted to the frame portion of the headmember, the roller having a groove 32 configured to receive anon-toothed portion 34 of the cutting blade within the groove of theroller. Accordingly, roller 30 provides a means for supporting thecutting blade as it reciprocates within a range of motion on the headmember.

In order to cause the cutting blade to traverse back and forth between afirst position (e.g., cutting blade fully extended away from a distalend of the head member) and a second position (e.g., cutting blade fullyretracted into the distal end of the head member) a source of compressedgas 36 is in selective fluid communication with a chamber (38, 40) ateither side of the piston to cause movement of the piston in thechamber, wherein movement of the piston causes movement of the cuttingblade by moving the rod and the mount. It being understood that size ofchambers 38 and 40 vary accordingly with the movement of the piston 18.In one non-limiting exemplary embodiment, the source of compressed gasis self-contained reservoir of carbon dioxide. Of course, other suitabletypes of compressed gas are considered to be within the scope ofexemplary embodiments of the present invention. In another exemplaryembodiment, the source of compressed gas is provided by a reservoirfluidly coupled to a compressor 29, which may be a stand alone device ora wearable unit.

In order to provide fluid communication between the source of compressedgas and chamber 38 a first valve 42 is provided to allow selective fluidcommunication between the source of compress gas and chamber 38 via aconduit 44. First valve 42 is configured to allow fluid communicationbetween the source of compressed gas and chamber 38 when the first valveis in an open position. Alternatively, and when the first valve is in aclosed position chamber 38 is in fluid communication with atmosphere sothat the gas in chamber 38 may be released to allow the cutting blade totravel to the first position. This is also provided by first valve 42and conduit 44. Accordingly, and when the first valve is closed, chamber38 via conduit 44 and first valve 42 allow the fluid in chamber 38 to bereleased into the atmosphere.

In order to provide fluid communication between the source of compressedgas and chamber 40 a second valve 46 is provided to allow selectivefluid communication between the source of compress gas and chamber 40via a conduit 48. Second valve 46 is configured to allow fluidcommunication between the source of compressed gas and chamber 40 whenthe second valve is in an open position. Alternatively, and when thesecond valve is in a closed position chamber 40 is in fluidcommunication with atmosphere so that the gas in chamber 40 may bereleased to allow the cutting blade to travel to the second position.This is also provided by second valve 46 and conduit 48. Accordingly,and when the second valve is closed, chamber 40 via conduit 48 andsecond valve 46 allow the fluid in chamber 40 to be released into theatmosphere.

In accordance with an exemplary embodiment of the present invention andin order to move the cutting blade to the first position the first valveis closed (e.g., gas vented from chamber 38) and the second valve isopen (e.g., gas supplied from source to chamber 40). Similarly and inorder to move the cutting blade to the second position the first valveis open (e.g., gas supplied from source to chamber 38) and the secondvalve is closed (e.g., gas vented from chamber 40).

In order to provide the opening and closing of valves 42 and 46 a slider50 is movably received within head member 14 wherein movement of theslider causes the first valve and the second valve to open and close. Inorder to effect the movement of slider 50 a rod portion 52 of the sliderhas a pair of stops 54 and 56 wherein a portion 58 of the mount 22 isslidably received upon the rod portion 52. As the cutting bladetraverses towards the first position the portion 58 will contact stop 54and cause first valve 42 to open and second valve 46 to close thus, thecutting blade will then traverse towards the second position wherein theportion 58 will contact stop 56 and cause first valve 42 to close andsecond valve 46 to open thus, the cutting blade will then traversetowards the first position. This reciprocal movement of the cuttingblade will continue until the source of gas is no longer fluidly coupledto the first valve and the second valve.

As illustrated in FIG. 4, the slider is slidably mounted above a coverplate 60 that is configured to allow slider 50 to open and close thefirst and second valves. Moreover, cover plate 60 is configured toprevent excessive wear from being caused by the reciprocal movement ofthe slider. In an alternative exemplary embodiment, the pneumaticallypowered pole saw is constructed without a cover plate (See FIGS. 5A-5D).

In order to provide fluid communication between the source of inlet orcompressed gas 36 and the first valve and the second valve a controlvalve 62 is configured to provide fluid communication between the sourceof inlet or compressed gas 36 and the first valve and the second valvevia conduits 64 between valve 42 and valve 46 and a conduit 68 betweensource of compressed gas 36 and control valve 62. In accordance with anexemplary embodiment of the present invention control valve 62 is in orproximate to head member 14 while conduit 68 extends to the source ofcompressed gas, which is disposed at an opposite end of a pole the headmember is secured to.

Referring now to FIGS. 5A-5D operation of an exemplary embodiment of thepresent invention is illustrated. FIG. 5A illustrates the saw bladetraveling in the direction of arrow 51. During this mode of operationand in the illustrated configuration of FIG. 5A valve 46 is open andcompressed gas is being released into chamber 40 while the gas ofchamber 38 is being released into the atmosphere from a vent of valve 42thus piston 18 and the saw blade travel in the direction of arrow 51. Itbeing understood that in order to effect movement in the direction ofarrow 51 valve 42 is closed to conduit 64 while valve 46 is open toconduit 64 since a first feature 53 of the slider is positioned toreceive a spring biased member 55 of valve 42 thus, causing conduit 64to be closed to chamber 38 while chamber 38 is open to atmosphere via avent 57 of valve 42.

In accordance with an exemplary embodiment of the present inventionmember 55 is biased generally into the direction of slider 50 such thatwhen member 55 is received into feature 53 of slider 50 conduit 64 isclosed to chamber 38 and vent 57 is open releasing the gas of chamber 38while the saw blade travels in the direction of arrow 51.

Movement of the saw blade in the direction of arrow 51 continues untilportion 58 contacts stop 54 (FIG. 5B) causing the slider 50 to translateinto the position of FIG. 5B wherein the feature 53 is no longer alignedwith member 55 and the same is depressed into valve 42 causing conduit64 to be in fluid communication with chamber 38 via valve 42 and conduit44. At this position, the vent 57 of valve 42 is closed and the pistonand saw blade will begin to travel in a direction opposite to arrow 51.Moreover, and at this position valve 46 is closed and the gas of chamber40 is being released into the atmosphere from a vent of valve 46. Itbeing understood that valve 46 is closed to conduit 64 while valve 42 isopen to conduit 64 since a second feature 59 of the slider is no longerpositioned to receive a spring biased member 61 of valve 46 thus,causing conduit 64 to be closed to chamber 40 while chamber 40 is opento atmosphere via a vent 63 of valve 46.

In accordance with an exemplary embodiment of the present inventionmember 61 is biased generally into the direction of slider 50 such thatwhen member 61 is received into feature 59 of slider 50 conduit 64 isclosed to chamber 40 and vent 63 is open releasing the gas of chamber 40while the saw blade travels in the direction opposite of arrow 51.Conversely, and when member 61 is not received into feature 59 of slider50 (FIG. 5A) conduit 64 is open to chamber 40 and vent 63 is closed andthe saw blade and piston travel in the direction of arrow 51.

Movement of the saw blade in the direction opposite of arrow 51continues (FIG. 5C) until portion 58 now contacts stop 56 (FIG. 5D)causing the slider 50 to translate back into the position of FIG. 5Awherein feature 53 is aligned with member 55 and feature 59 is notaligned with member 61 causing conduit 64 to be in fluid communicationwith chamber 40 via valve 46 and conduit 48. At this position, the vent57 of valve 42 is open and the piston and saw blade will begin to travelin the direction of arrow 51. It being understood that valve 46 is opento conduit 64 while valve 42 is closed to conduit 64 since the secondfeature 59 of the slider is no longer positioned to receive springbiased member 61 of valve 46 thus, causing conduit 64 to be open tochamber 40 while chamber 38 is open to atmosphere via vent 57 of valve42.

In accordance with an exemplary embodiment of the present invention,this reciprocal movement of saw blade 12, piston 18 and slider 50 willcontinue until the source of compressed gas released into conduit 64 byvalve 62 ceases.

In accordance with an exemplary embodiment and by having the controlvalve at or proximate to the head member conservation of the gas supplyis provided as conduit 68 will traverse through the pole which can be 20feet or longer thus, and if the pole saw was required to fill orenergize conduit 68 with gas each time the pneumatically powered polesaw was activated the source of compressed gas will be depleted quicker.Of course, the pole may be of any length (e.g., 10 feet or shorter, 8feet or shorter, 6 feet or shorter, etc.). A non-limiting range for thelength of the pole may be 5-25 feet. In accordance with an exemplaryembodiment conduit 68 is filled with the gas and control valve 62 turnsthe saw on and off by limiting the amount of gas supplied via source ofgas 36.

In one non-limiting exemplary embodiment, control valve 62 is an electromechanical valve activated by a switch 70 disposed at an end of thepneumatically powered pole saw opposite from the cutting blade. Inanother non-limiting exemplary embodiment, control valve 62 is apneumatically activated valve wherein a fluid conduit 72 provides fluidcommunication with the source of compressed gas and switch 70 allowsfluid communication between valve 62 and source of compressed gas 36wherein the compressed gas will open valve 62 and gas will be suppliedto valves 42 and 46. In this embodiment, and in order to conserve thefluid supply of compressed gas 36 conduit 72 is much smaller thanconduit 68 and thus only a small amount of gas is wasted each time valve62 is opened. Furthermore, switch or valve 70 can be operated at a muchlower pressure than the pressure passing through conduit 68 and isnecessary to manipulate the movement of the piston within the cylinder.

Referring now to FIG. 6 a pneumatically powered pole saw 10 constructedin accordance with an exemplary embodiment of the present invention isillustrated here a source of compressed gas 36 is a bottle secured to anend of a pole 78. In this embodiment, conduit 68 and/or conduit 72traverse the length of pole 78 until they reach control valve 62, whichdisposed in or proximate to head portion 14. Thus, a user 80 activatesthe pneumatically powered pole saw by manipulating switch 70 and the sawis activated to cut a limb 82 of a tree 84. Once the desired task iscompleted, switch 70 is moved to an off position and the remaining gasis eventually released from the head member.

FIG. 7 illustrates an alternative exemplary embodiment, wherein thesource of compressed gas 36 is secured to a wearable belt or harness 86thus, the individual wears the compressed gas and the same is secured tothe conduit 68 of the pole via a flexible conduit 88. Here the weight ofthe compressed gas is not on the end of the pole making the same easy tomanipulate and use.

Referring now to FIG. 1A an alternative exemplary embodiment of thepresent invention is illustrated. Here frame portion 28 furthercomprises a stop member 120. In an exemplary embodiment, stop member 120has a pair of arms 122 and a cross member 124 that define a stop forlimb that is being cut by the pole saw. For example, and as the blade isdrawn towards the stop the teeth of the blade will engage the limb andapply a downward force to the limb which in turn may cause the headmember to be drawn upward or in an opposite direction to the force beingapplied to the limb as the blade travels down towards the stop member.Accordingly, and in order to impart the cutting force to the limb in adownward stroke of the blade the stop member provides a surface toreceive a portion of the limb on as the blade travels downward towardsthe stop member. Alternatively, and as illustrated by the dashed linesin FIG. 1A, the frame portion 28 is configured to extend past roller 30and enclose the same within a portion of the frame portion so that limbsbeing cut or not being cut do not interfere with the movement of roller32.

Referring now to FIGS. 1B-1D alternative configurations of the saw bladeare illustrated. FIG. 1B illustrates a straight saw blade wherein awidth 130 of the blade from the non-toothed portion 34 and a toothedportion of the blade is essentially the same thickness along an edge 132that is received within groove 32 of roller 30. Accordingly, and in thisembodiment, the teeth of the blade generally act upon a cutting surfacein a linear fashion.

Alternatively, and referring now to FIG. 1C, the width 130 of the bladefrom the non-toothed portion 34 and a toothed portion of the blade isnot the same thickness along an edge 132 that is received within groove32 of roller 30. Accordingly, and in this embodiment, the teeth of theblade generally act upon a cutting surface in a non-linear or curvedfashion as the toothed surface also has a curved configuration.

In yet another alternative, and referring now to FIG. 1D, the width 130of the blade from the non-toothed portion 34 and a toothed portion ofthe blade is not the same thickness along an edge 132 that is receivedwithin groove 32 of roller 30. Accordingly, and in this embodiment, theteeth of the blade generally act upon a cutting surface in a non-linearfashion as the saw blade is reciprocated within a range of motion andthe teeth are acting upon a cutting surface.

In addition, and in accordance with one non-limiting exemplaryembodiment of the present invention the stroke of the saw blade isapproximately 4 inches which has been found to be suitable for tree limbcutting operations. Of course, strokes greater or less than 4 inches areconsidered to be within the scope of exemplary embodiments of thepresent invention.

In an alternative exemplary embodiment, the piston may be spring biasedinto one of the positions illustrated in FIGS. 5A-5D such that one ofthe valves 42 or 46 is open at an initial starting point and movement tothe next position will be caused by the piston overcoming the springforce as well as the gas pressure on one side of the piston. In anotherexemplary embodiment, a spring biasing member may be positioned oneither side of the piston wherein one spring biasing force is greaterthan the other to maintain one of the positions illustrated in FIGS.5A-5D such that one of the valves 42 or 46 is open at an initialstarting point.

Referring now to FIGS. 9A-11B, a pneumatically powered pole saw 10constructed in accordance with an alternative embodiment of the presentinvention is illustrated. Here, referring to FIGS. 9B and 10B and inorder to provide fluid communication between the source of compressedgas and chamber 40 a reciprocating valve 132 is provided to allowselective fluid communication between the source of compressed gas andchamber 40 via a conduit 134. In one non-limiting exemplary embodimentthe reciprocating valve is a Humphrey Products TAC Valve (See FIGS. 10Aand 10B). One non-limiting description of a Humphrey Valve is found inU.S. Pat. No. 6,488,050 the contents of which are incorporated herein byreference thereto. When the reciprocating valve is in a first position(See FIGS. 9B and 10B), a first outlet 136 of reciprocating valve is influid communication with a fluid inlet 138 of reciprocating valve whichis in fluid communication with an inlet conduit 139 which is in fluidcommunication with the source of compressed gas to allow fluidcommunication between the source of compressed gas and chamber 40.

Alternatively, and as illustrated by the dashed lines in FIG. 9A as wellas in FIGS. 10A and 11A, when the reciprocating valve is in a secondposition, the first outlet 136 restricts fluid communication between thesource of compressed gas and chamber 40 and chamber 40 is in fluidcommunication with the atmosphere so that the gas in chamber 40 may bereleased via opening a first check valve 140 disposed on conduit 134 toallow the cutting blade to travel to the second position. In stillanother embodiment, the first check valve is disposed proximate tochamber 40. Accordingly, and when the reciprocating valve is in thesecond position, chamber 40 via first check valve 140 allows the fluidin chamber 40 to be released to the atmosphere.

Referring back to FIGS. 9A and 10A and in order to provide fluidcommunication between the source of compressed gas and chamber 38 areciprocating valve 132 is provided to allow selective fluidcommunication between the source of compressed gas and chamber 38 via aconduit 142. When the reciprocating valve is in a second position (SeeFIGS. 9A and 10A), a second outlet 144 of reciprocating valve is influid communication with the fluid inlet 138 of reciprocating valvewhich is in fluid communication with the inlet conduit 139 which is influid communication with the source of compressed gas to allow fluidcommunication between the source of compressed gas and chamber 38.

Alternatively, and as illustrated by the dashed lines in FIG. 9B as wellas in FIGS. 10B and 11B, when the reciprocating valve is in a firstposition, the second outlet 144 restricts fluid communication betweenthe source of compressed gas and chamber 38 and chamber 38 is in fluidcommunication with the atmosphere so that the gas in chamber 38 may bereleased via opening a second check valve 146 disposed on conduit 142 toallow the cutting blade to travel to the first position. In onenon-limiting exemplary embodiment, the second check valve is disposedproximate to chamber 38. Accordingly, and when the reciprocating valveis in the first position, chamber 38 via second check valve 146 allowsthe fluid in chamber 38 to be released to the atmosphere.

In accordance with an alternative embodiment of the present inventionand in order to move the cutting blade in the first cutting direction,the reciprocating valve 132 is in the first position (e.g. gas suppliedfrom source to chamber 40) and the second check valve 146 is opened(e.g. gas vented from chamber 38). Similarly, and in order to move thecutting blade to the second cutting direction the reciprocating valve132 is in the second position (e.g. gas supplied from source to chamber40) and the first check valve 140 is opened (gas vented from chamber40).

In order to provide the movement between the first and second positionsof the reciprocating valve 132 an actuator 148 is disposed within thereciprocating valve wherein movement of the actuator 148 causes thereciprocating valve to move between the first and second positions (SeeFIGS. 9A-10B). In order to effect the movement of the actuator anassembly 150 is slidably mounted in the head member. The assembly alsohas a pair of fixedly secured stops 152 and 154 wherein a portion 156 ofthe cutting blade is slidably received upon the assembly. As the cuttingblade traverses in the first cutting direction the portion 156 of thecutting blade will contact stop 152 and cause the assembly 150 to moveand contact the actuator causing movement of the reciprocating valve tothe second position causing first check valve 140 to open thus, thecutting blade will then traverse in the second cutting direction whereinportion 156 will contact stop 154 and cause the assembly to move andcontact the actuator causing movement of the reciprocating valve to thefirst position causing second check valve to open thus, the cuttingblade will then traverse to the first cutting position. This reciprocalmovement of the cutting blade will continue until the source of gas isno longer fluidly coupled to the inlet 132 of the reciprocating valve.

As illustrated in FIGS. 9A and 9B, the assembly further comprises a mainrod member 158 for slidably receiving the portion 156 of the cuttingblade and a pair of contact members 160 and 162 each fixedly secured tothe main rod member 158. Moreover, the actuator comprises a pair ofcontact sides 164 and 166 (See 10A and 10B) associated with the pair ofcontact members 160 and 162 wherein contact member 160 contacts contactside 164 when the portion 156 of cutting blade makes contact with stop154 causing assembly to move in the second cutting direction, andsimilarly, contact member 162 contacts contact side 166 when the portion156 of cutting blade makes contact with stop 152 causing assembly tomove in the first cutting direction. It being understood that the pairof contact members 160 and 162 are not fixedly secured to the contactsides 164 and 166 of the actuator such that when contact member 160 isin contact with contact side 164 a spaced relationship or gap existsbetween contact member 162 and contact side 166. Similarly, when contactmember 162 is in contact with contact side 166 a spaced relationship orgap exists between contact member 160 and contact side 164.

In one non-limiting alternative embodiment of the present invention apair of biasing members 153 and 155 disposed proximate to stops 152 and154 provides portion 156 to be biased in the opposite direction whenportion 156 makes contact with stop 152 or 154. It being understood thatbiasing members 153 and 155 are disposed on the side opposite to contactsurface between portion 156 of and respective stop 152 or 154. Referringto FIG. 9A, when portion 156 makes contact with stop 152 assembly movesto the first cutting direction and portion 156 is subsequently biased tothe second cutting direction due to the force provided by biasing member153. Similarly, referring to FIG. 9B, when portion 156 makes contactwith stop 154 assembly moves to the second cutting direction and portion156 is subsequently biased to the first cutting direction due to theforce provided by biasing member 155.

Referring to FIGS. 9A-11B operation of an alternative embodiment of thepresent invention is illustrated. It being understood that FIGS. 11A and11B illustrate check valves 140 and 146 in a venting position (FIG. 11B)wherein the gas from the piston chambers 38, 40 moves the diaphragm 178and in a supply position (FIG. 11A) wherein compressed gas is suppliedvia inlet 176 and the same moves the diaphragm 178 to cover the valveseat 180 and prevent fluid communication to outlet 184. In other wordsthe configurations of valve 140 and 146 are similar thus, two figuresare used to show the two positions of the two valves each being inselective fluid communication with either side of the piston chamber. Itbeing further understood that outlets 184 of valves 140 and 146 are opento atmosphere to allow for unimpeded movement of the saw blade by thealternating supply of the compressed gas to the piston chambers ateither side of the movable piston. In accordance with an exemplaryembodiment, the diaphragm 178 is constructed out of a resilient pliablematerial such as rubber or equivalents thereof such that the same can bemoved by the gas from chambers 38 and 40 or the supply inlet 176. FIG.9A illustrates the saw blade moved in the first cutting direction 157.During the traverse from the second cutting direction (opposite to arrow157) to the first cutting direction reciprocating valve 132 is in thefirst position (See FIG. 10B) wherein second check valve 146 is open(FIG. 11B) thereby venting gas from chamber 38 to the atmosphere whilefirst outlet 136 is in fluid communication with inlet 138 allowing fluidcommunication between the source of compressed gas and chamber 40 viacheck valve 140 (FIG. 11A) thus piston 19 and the saw blade travel inthe first cutting direction. It being understood that in order to effectmovement towards the first cutting direction the second outlet 144 isclosed to conduit 142 and the first outlet is in fluid communicationwith conduit 134 since a first seal 168 is seated within a first seat170 thereby opening first outlet 136 thus, causing conduit 134 to be influid communication with chamber 40. Similarly, a second seal 172 isunseated from a second seat 174 thereby sealing second outlet 144 thus,causing conduit 146 to be closed to chamber 38 while chamber 38 is opento atmosphere via second check valve 146 (FIG. 11B).

Referring now to FIGS. 9B and 11B, second check valve 146 is in anun-actuated position (FIG. 11B) configured to release gas from chamber38 to the atmosphere when compressed gas is not entering through aconduit inlet 176 thereby causing a diaphragm 178 to not close against avalve seat 180 so that compressed gas from chamber 38 via piston passage182 may vent directly to the atmosphere through an atmosphere outlet 184instead of venting through the entire length of conduit 142. Moreover,the pressure caused by the piston travelling in the direction of arrow157 from the position in FIG. 9B to the position in FIG. 9A causes thediaphragm 178 in valve 146 to move up to the position illustrated inFIG. 11B. This is particularly advantageous because allowing thecompressed gas to vent from chamber 38 more quickly allows lessback-pressure to retard the movement of the piston 18. Similarly,referring to FIGS. 9B and 11A and as the blade travels in a directionopposite to arrow 157, first check valve 140 is in an actuated position(FIG. 11A) configured to supply compressed gas to chamber 40 through theconduit inlet 176 thereby causing diaphragm 178 to close against valveseat 180 and diaphragm 178 has a peripheral configuration so thatcompressed gas may be supplied to chamber 40 via piston passage 182 andas illustrated by the arrows in FIG. 11A since the compressed gas forcesthe diaphragm against valve seat 180.

In one non-limiting alternative embodiment of the present inventionfirst and second check valves 140, 146, are disposed proximate tochambers 40, 38, respectively, in order maintain the least amount ofback pressure as possible between supplying and venting the compressedgas to chambers 38 and 40.

Referring now to FIGS. 9B and 10A movement of the saw blade in thesecond cutting direction opposite to arrow 157 is illustrated. Duringthe traverse from the first cutting direction to the second cuttingdirection reciprocating valve 132 is in the second position (See FIG.10A) wherein first check valve 140 is open (FIG. 11B e.g., no gasprovided to inlet 176) thereby venting gas from chamber 40 to theatmosphere while second outlet 144 is in fluid communication with inlet138 allowing fluid communication between the source of compressed gasand chamber 38 via valve 146 in the position illustrated in FIG. 11Athus piston 18 and the saw blade travel in the second cutting direction.It being understood that in order to effect movement towards the secondcutting direction the first outlet 136 is closed to conduit 134 and thesecond outlet 144 is in fluid communication with conduit 142 since thesecond seal 172 is seated within the second seat 174 thereby openingsecond outlet 144 thus, causing conduit 142 to be in fluid communicationwith chamber 38. Similarly, the first seal 168 is unseated from thefirst seat 170 thereby sealing first outlet 136 thus, causing conduit134 to be closed to chamber 40 while chamber 48 is open to atmospherevia first check valve 140.

Referring now to FIGS. 9A and 11B, and as the blade moves in the secondcutting direction, first check valve 140 is in an un-actuated positionconfigured to release gas from chamber 40 to the atmosphere whencompressed gas is not entering through the conduit inlet 176 therebycausing the diaphragm 178 to not close against the valve seat 180 sothat compressed gas from chamber 40 via piston passage 182 may ventdirectly to the atmosphere through an atmosphere outlet 184 instead ofventing through the entire length of conduit 134. This is particularlyadvantageous because allowing the compressed gas to vent from chamber 40more quickly allows less back-pressure to retard the movement of thepiston 18. Similarly, referring to FIGS. 9A and 11A, second check valve146 is in an actuated position configured to supply compressed gas tochamber 38 through the conduit inlet 176 thereby causing diaphragm 178to close against valve seat 180 so that compressed gas may be suppliedto chamber 38 via piston passage 182.

In accordance with an alternative embodiment of the present invention,this reciprocal movement of cutting blade 12, piston 18, reciprocatingvalve 132 and assembly 150 will continue until the source of compressedgas released into the inlet conduit 139 in fluid communication withinlet 138 of reciprocating valve ceases.

Referring now to FIGS. 9A and 9B an alternative embodiment of thepresent invention is illustrated. Here a frame portion 186 comprises astop member 188 secured to the end of the frame and extending outwardtoward the end of the cutting blade 12. Stop member 188 defines a stopfor a limb that is being cut by the pole saw. For example, and as theblade is drawn towards the stop the teeth of the blade will engage thelimb and apply a downward force to the limb which in turn may cause thehead member to be drawn upward or in an opposite direction to the forcebeing applied to the limb as the blade travels down towards the stopmember. Accordingly, and in order to impart the cutting force to thelimb in a downward stroke of the blade the stop member provides asurface to receive a portion of the limb on as the blade travelsdownward towards the stop member.

Referring now to FIGS. 12A-19C other alternative embodiments of thepresent invention are illustrated. In one embodiment, the main valvesare moved by an intermediary device called a pilot valve, which deliverscompressed gas to actuate the main valves. Utilizing pneumatic pilotvalves to actuate pneumatic main valves instead of directly actuating bymechanical arms, rods levers or sliders is desirable in that pilot valvepneumatic actuation of the main valves does not leave the main valves inan undetermined state, that is, in a “dead zone” position wherein allmotion stops. A dead band or dead zone is a place where the valves arechanging fluid flow states. This valve transition is where valves canstall and reciprocating motion can stop. This dead zone transitionproblem is particularly noticeable at extremes of reciprocation speed.For example, at slow speed, where valve actuators are moving veryslowly, the main valves can pass too slowly through this dead zone statewherein both main valves' ports are partially open and partially closed.Since there is not sufficient momentum of the mechanical main valveactuators during slow speed to move the valves quickly through thisstate the valves stop in the dead zone where compressed gas is appliedequally to both sides of the piston cylinder, and the piston and valvesare therefore not being driven either direction and thus they arestalled.

In this embodiment, the pneumatically powered pole design utilizes pilotvalves that provide compressed gas to actuated main valves. The primaryadvantage in the use of compressed gas pilot valves in this embodimentis exceptionally reliable actuation of the main valves, especially giventhe wide variation of reciprocation speed and with no rotational mass orcentrifugal force to assist in the valve transition dynamics. Pneumaticactuation eliminates the problem of dead zone failure.

At the end of travel of the piston, a pilot valve is actuated whichprovides compressed gas energy to a main valves assembly, forcing themain valves through the dead zone and into proper state positionsbecause of the steady force applied by the compressed gas. The mainvalves do not bounce back from their limits of travel at highreciprocation speeds because the gas pressure provided by the pilotvalve holds the main valve momentarily in position. Nor will the mainvalves stall in the dead zone at slow speeds because the compressed gasfrom the pilot valve continues to force the main valves into properposition until the main valves' state transition has been completed.

FIGS. 12A-18E illustrate an embodiment of a pneumatically actuated polesaw with pilot valve actuation of the main valves. FIGS. 12A and 12Billustrate an external assembly view and the physical relationships ofvarious components including pole 124, blade 108, blade roller 109, limbstop 123, main valves assembly 128, pilot valve 118, pilot valve 119,compressed gas inlet 117, and compressed gas splitters 132.

The FIGS. provide top level and sectional views through which viewinternal components including pilot valve actuator 120, piston cylinder100, piston 106, piston rod 121 and main valves assembly 128 can beviewed. The internal views show the piston pushing the blade outwardfrom the pole and the end of travel of piston 106 in this blade pushdirection pilot valve actuator 120 makes contact with pilot compressedgas actuator 119 (FIG. 12E) and FIG. 13C illustrates the reciprocatingpiston 106 at the end of travel in the blade pull direction where pilotvalve actuator 120 attached to piston rod 121 is in contact with pilotvalve 118.

At least FIGS. 14A, 14B, 15A, 15B, illustrate details of the reciprocalfunctioning. As illustrated, the piston cylinder 100 is held securely topole 124 by a mount 122 so that compressed gas energy suppliedalternatively to each side of the piston 106 by main valves assembly 128forces piston rod 121 attached to blade 108 through coupling 126 andclevis pin 107 to reciprocate thereby provide gas powered cutting motionto the blade.

Referring at least to FIG. 14A, pneumatically actuated main valve 128has an internal shuttle 135, which is compressed gas actuated, andreciprocates between two distinct locations by means of gas pressureapplied to opposite ends of 135 through tubing from two smallmechanically actuated pilot valves 118 and 119 positioned so they arealternatively actuated at the ends of travel of the main piston rod 121.The main valve 128, is seen from non-cutaway views of at least FIGS. 14Band 15B. FIGS. 14A and 15A show the main piston 106 in alternatepositions in order to illustrate a full reciprocating cycle and theinteraction of the pilot valves with the pneumatically actuated mainvalves of assembly 128.

FIG. 15A shows when compressed gas comes through the pole saw via tube117. A portion of the gas then comes through primary gas flow splitter132 to tube 116 into gas flow splitter 133 through tubes 114 and 115 tothe mechanically actuated pilot valves 118 and 119 while most of the gasflow volume is conducted from primary flow splitter 132 through tube 131and fitting 130 into the main 4-way valve 128. Compressed gas cominginto main 4-way valve 128 is directed past the internal shuttle 135 andout of main valve 128 through tube 104 to inlet fitting 102 into thepiston cylinder where it applies gas pressure to slideable piston 106.Gas pressure is kept from leaking around slideable piston 106 by meansof piston seal 105. Compressed gas in the chamber on the opposing sideof piston 106 is vented out of chamber 127 through fitting 101 into tube103 and out of main valve 128 through vent orifice 129. Gas pressure inthe piston chamber moves piston 106 attached to piston rod 121, which islinked to cutting blade 108 through blade attach rod and bracket 126 and107, forces saw blade 108 to move in the pull direction.

After some travel in the pull direction the actuator 120 attached to theend of piston rod 121 opposite from the end where blade 108 is attachedcontacts pilot valve 118. Pilot valve 118 when contacted by mechanicalactuator 120 directs a pulse of gas from splitter 133 through tube 114then through pilot valve 118 into tube 112 and into main valve 128 whichpulse of gas moves internal shuttle 135 located within main valve 128such that the primary gas supply coming into main valve 128 throughfitting 130 is redirected to tube 103 and fitting 101 into chamber area127 of cylinder 100 and applies pressure against piston 106 forcingattached piston rod 121 to move saw blade 108 in the push direction andpilot valve actuator 120 attached to rod 121 to move in direction towardpilot valve 119. When gas pressure is increased in piston chamber 127gas pressure on the opposite side of piston 106 and inside of cylinder100 needs to be vented to reduce pressure that would oppose movement ofpiston 106 in the blade push direction, and the vent gas moves throughfitting 102 into tube 104 though main valve assembly 128 and out intothe atmosphere through vent orifice 136.

Referring now to at least FIG. 14A, when valve actuator 120 makescontact with pilot valve 119 a pulse of gas is conveyed from splitter133 through tube 115 then through the opened valve 119 to tube 113 andon to connector 111 into main valve 128, which pulse of gas movesinternal shuttle 135 such that the primary gas supply coming into valve128 through fitting 130 is then directed to tube 104 and fitting 102into the piston chamber providing pressure against piston 106 andforcing piston rod 121 connected through blade attach bracket 126 toblade 108 and causing saw blade 108 to return to a powered pull cuttingstroke.

Accordingly and in this embodiment, pilot valves are used to gas actuatea main valves assembly to reciprocally drive a piston linked to thecutting blade of the pole saw.

Referring now to at least FIGS. 16-19C the functionality of the valvesand the pistons and associated motion dynamics of various embodiments ofalternative exemplary embodiments of the present invention areillustrated wherein detailed views illustrate the position of the pistonand valves.

FIG. 16A shows a portion of the valving with the piston in mid traveland the pilot valves venting. FIG. 16E also shows the piston inmid-travel and the pilot valves venting and illustrates the valveassembly on the blade side of the piston cylinder.

FIGS. 17B and 17E illustrate expanded views of the valve assemblies onopposite ends of the piston chamber. FIG. 17E illustrates that thepiston is fully retracted in the blade pull stroke position and pilotvalve 236 is shown as being actuated.

FIGS. 18B and 18E are similar views to FIGS. 17B and 17E however, theblade is in the fully extended position and pilot valve 229 is shown asbeing actuated.

Referring now to FIGS. 19-19C, ball bearings are illustrated as beingattached to the blade. FIG. 19C shows details of the blade stop end withthe pole bearing and blade in conjunction with a limb in order todescribe limb cutting action by the blade.

In another embodiment, the piston cylinder and valves are shifted awayfrom the blade though the use of a rod extension 303, and piston rod 202(See at least FIG. 16A). Through the use of a light-weight rod extension303 the weight of the piston and valve assemblies are moved away fromthe blade end of the pole. Repositioning the weight in this manner makesit easier for the operator to balance, align and position the pneumaticpole saw for cutting in a tree.

In accordance with one embodiment of the present invention, the pistoncylinder 216 and related valve sub-assemblies 221 and 236 arerepositioned away from the cutting blade 316 by inserting a light weightrod extension 303, between the piston rod 202 and the blade 316. Thisallows the weight of the piston cylinder 216 and valves closer to berepositioned closed to the person holding the other end of the pole,which is opposite from the blade end of the pole. Accordingly, thecenter of weight of the apparatus is shifted back from the blade end ofthe pole making it easier for the operator to hold, position, andbalance the pole saw in operation. In an alternative embodiment, thisshifting in weight could also be achieved by means of cable and pulleyto couple reciprocating power between the actuator and blade.

In another embodiment of the present invention and as illustrated in atleast FIGS. 16-16E the pilot valves 236 and 221 and associated mainvalves, 210 and 223 located on the same axis as the piston rod 202,thereby reducing the physical diameter of the pole saw so that thevalves can be located within the pole saw housing and thus reduce thediameter and/or profile of the pole saw such that is can more easilyreach between branches of a tree. As illustrated in the attached FIGS.,the pilot valves 236 and 221 and associated main valves, 210 and 223 arepositioned about or axially about the piston rod 202 extending fromopposite sides of the piston 215. The pilot valves 236 and 221 andassociated main valves, 210 and 223 are also configured such that thepistion rod 202 can be slidably received within the pilot valves 236 and221 and associated main valves, 210 and 223 such that reciprocalmovement of the piston 215 and rod(s) 202 can be achieved. In addition,the pilot valves 236 and 221 and associated main valves, 210 and 223 arealso sildably received within housings 259 and 271 threaded onto theirrespective ends of piston cylinder 216. Still further, the housings 259and 271 and the piston cylinder 216 are received within the housing orpole of the pole saw.

In alternative embodiments, the pilot valves 236 and 221 and associatedmain valves, 210 and 223 can be located on the same side of the pistoncylinder or adjacent to the piston cylinder.

The placing of these pilot and main valves on axis such that the pistonrod goes through the center of the pilot and main valves allows thevalves to be in close proximity to the piston cylinder while still beinginside the pole. In contrast and as illustrated in FIGS. 12A-15B, themain valves assembly 128 is in close proximity to the piston cylinder tooptimize power efficiency but because neither main valves assembly 128nor associated pilot valves 118 and 119 are inside of the pole theoverall saw dimensions in this portion of the pole saw are larger thanthose illustrated in FIGS. 16-18E.

Although FIGS. 16-19 and 19B illustrate external tubing, this is merelyprovided as a non-limiting embodiment to illustrate and describe thepneumatic gas flow in each of the tubes. It is, of course, understoodthat in one non-limiting exemplary embodiment, these tubes will be inintimately close proximity to the pole and/or internal to the housing ofthe pole.

As shown in FIGS. 16-18E, the main valves assembly have been separatedinto two valve subassemblies. In FIG. 12-15B the main valves assemblyhad the 4 way valves connected together so that if one moved to a newstate the opposing one moved simultaneously. In FIGS. 16A-18E each mainvalve in the valve subassembly has a pilot valve nearby and both mainand pilot valve are housed in the cylinders to form valve subassemblies221 and 236. These valve subassemblies are threaded onto theirrespective ends of piston cylinder 216. Placing the valve subassembliesat opposite ends of the piston cylinder reduces the distance between theindividual main valves and their respective piston cylinder gas inlets,improves power efficiency by reducing compressed gas losses during mainvalve switching. This improvement in power efficiency is due to closephysical proximity and shorter coupling tubes.

Alternative embodiments of the pneumatic valve architecture in additionto those shown in the embodiments of the attached FIGS. Thesealternative embodiments would employ separate pilot valve or valves toactuate compressed gas driven main valves. One such alternativeembodiment would be to place both main valves on the same end of thepiston cylinder, still actuating by pilot valves on the same end or onopposite ends of the piston cylinder. Such valve architectures wouldvary in power efficient, in complexity of valve architecture, and incenters of weight.

As illustrated in at least, FIGS. 16A-16B, 16D and 16E each end ofpiston cylinder 216 has attached to it one of the two valvesub-assemblies 236 and 231. Each of these valve assemblies includes apilot valve, a main valve, and associated conductive tubing. In onenon-limiting exemplary embodiment, the valve subassemblies are attachedby thread to the ends of the piston cylinder. On one end, the endclosest to blade 316, is located valve sub-assembly 236 containing pilotvalve 205 and main valve 210. On the other end of the piston cylindervalve sub-assembly 221 containing pilot valve 229 and main valve 223 islocated.

As illustrated in at least FIGS. 18D and 18E piston 215 attached topiston rod 202, has finished moving in blade push direction wherebyblade 316 is fully extended outward. A spring 257 (FIG. 18B) moved bypiston rod end 258 has contacted bushing 255 and pushed it into pilotvalve 229, which has released compressed gas which has flowed from inlettube 256 into inlet gas manifold 241 to gas tube 246 through the nowactuated pilot valve 229 into tube 209 to be conducted to fittings 220of main valve 223 and also from fitting 220 to inlet fitting 253, (SeeFIG. 18E), and into the actuation side of the other main valve 210. Mainvalve 223 is forced by pilot gas pressure to move away from the pistoncylinder 216 and moves into a position to block gas from inlet tube 256through fitting 248 while main valve 223 simultaneously vents gas fromthe piston chamber through transfer tube 218 through main valve 223 andout vent 249. Pilot gas from valve 229 supplied as described throughtube 209 has simultaneously passed through tube 209 to fitting 253 andinto main valve 210 actuating 210 toward piston cylinder 216, main valve210 thereby allowing compressed gas from inlet tube 256 through manifold241 through tube 239 into now open main valve 210 into transfer tube 211into the piston cylinder to apply gas pressure onto this side of thepiston chamber and forcing the piston 215 with O-ring seal 240 to nowtransition to an opposite direction which will result in force beingapplied through piston rod 202 which is linked mechanically through rodextension 303 to the cutting blade 316 and which results in now pullingthe cutting blade inward and toward the piston cylinder 216.

Referring to FIGS. 17-17E, as the piston continues in this blade pulldirection spring 201 mounted on piston rod 202 will eventually contactbushing 203 forcing pilot valve 205 (FIG. 17E) to move toward valve stop208, compressing pilot valve return spring 232 and repositioning pilotvalve 205 such that compressed gas from manifold 241 through tube 234into fitting 231 is conducted through now actuated pilot valve 205 tothrough fitting 206 into tube 207 simultaneously providing compressedgas to main valve 210 through fitting 212 and also into main valve 223through fitting 224. Compressed gas from pilot valve 205 thereby forcesmain valve 210 to moves in a direction outward and away from pistoncylinder 216, main valve 210 thus being forced into a new position whichblocks compressed gas from manifold 241 through tube 239 from passingout of fitting 238. Main valve 210 does now allow compressed gas on theadjacent side of the piston cylinder to vent out through transfer tube211 and through main valve 210 and out to atmosphere through vent 236.

While main valve 210 has been actuated to vent the adjacent side ofpiston chamber 216, main valve 223 has been simultaneously activated bypilot valve 205 through tube 207 to move in a direction which allowscompressed gas from manifold 241 through tube 247 to fitting 248 throughmain valve 223 into transfer tube 218 to be conducted into the pistoncylinder. Compressed gas flowing into the piston cylinder will force thepiston 215 in a direction that allows for a push stroke of the pistonrod linked to the cutting blade 316. When this push stroke of the pistonreaches its limit of travel pilot valve 229 will again be actuated byspring 257 as shown in FIGS. 18-18E the reciprocation cycle will beginagain to now repeat the pull stroke motion linked to the cutting blade316 through connecting rod 303. The above has described a full cycle ofreciprocating motion of the pilot valve controlled independently gasactuated main valve architecture of this embodiment of pneumaticallypowered pole saw.

Referring now to FIGS. 19-19C views and in some instances sectionalviews of a rectangular pole section 304 is provided. Of course, otherconfigurations in addition to rectangular are contemplated. Section 304is the portion of pole a rectangular aluminum extrusion within which thecutting blade is attached to rod extension 303 which in turn ismechanically linked to piston rod 202 to transfer reciprocating powerfrom the actuating piston 216 to cutting blade 316 as shown in as leastFIG. 16A. In one embodiment, there is a pin mounted roller bushing 312mounted at the end of the pole 304 which, in combination with bearingsets 321 and 322, function to guide blade 316 while minimizingfrictional resistance to the reciprocating motion of blade 316. Bushing312 further constrains the directional force on blade 316, which occurswhen blade 316 is cutting a limb 317 shown in FIG. 19C.

In one non-limiting embodiment, the bearing sets 321 and 322 eachcomprise two ball bearings, one located on each side of the blade 316,the individual bearings of each set are attached together by press pinand with bearing sets 321 and 322 located on the end of blade 316 whichis in proximity to the coupling point of rod extension 303. Bearing sets321 and 322 rolling inside of the rectangular section of pole 304 guidethe blade while minimizing hardware complexity and weight needed inproviding the blade guide function.

As illustrated in FIG. 19B a section of the pole has been cut away nearpneumatic control switch 320 because the typical light weightpneumatically actuated pole saw will be five to eight meters in length.This length does not lend itself to detailed viewing of internal partswithout visual removal of a section of the pole thus shortening itsappearance in FIG. 19B. As illustrated in the attached FIGS. and bymoving weight away from the blade end of the pole and towards theoperator the pole saw is balanced to provide control and positioning ofthe pole saw as it is extended to cut a tree as illustrated in FIG. 16Aby effectively extending piston rod 202 through use of light weight rodextension 303. This rod extension 303 results in the weight of thepiston cylinder and associated valves being shifted down the pole towardthe operator, making it easier for the operator to balance and align andposition the pneumatic pole saw for cutting. The necessary extendedconnection between the piston rod and the blade can be achieved by otherthan a rod (e.g., cable and pulley or any other equivalent means). Yetanother means would be the use of a single ended piston with a springreturn on the blade and a spring return on the piston then only a cablewould be required to transfer power between the piston and the blade,wherein the blade return spring would provide power for the push strokeof the blade.

In one non-limiting exemplary embodiment, a compressed gas switchingpneumatic valve assembly is provided. The valve assembly comprising anouter pneumatic chamber, a slidably received gas sealed valve memberwithin the pneumatic chamber, an internal void extending from one sideof the pneumatic chamber to another side of the pneumatic chamber, thevoid allowing axial location of the pneumatic valve assembly around anaxial located piston rod of a pneumatic piston chamber, the pneumaticvalve assembly further comprising two or more gas conductive ports andconduits to conduct switchable gas fluid flow into and out of thepneumatic chamber when slidably received valve member is externallyactuated to change position within the pneumatic chamber.

In another non-limiting embodiment, the pneumatic valve assembly isconfigured as a pilot valve, the pneumatic valve chamber being axiallylocated and attachable on one end to a piston chamber, the internalpneumatically sealed slidable spring returned valve member is actuatedto alternate gas flow position by end effector on axial piston rod suchthat motion of the slidable valve member switches compressed gas fluidflow through fluid conducting port and conduit from inward gas fluidflow to outward gas fluid flow and removal of piston rod mounted endeffector from actuation of valve member allows spring return of thevalve member whereby gas flow is switched from outward fluid flow toinward fluid flow direction.

Still further and in yet another embodiment, the valve assembly isconfigured as a main valve, the pneumatic valve chamber being axiallylocated around the piston rod of a pneumatic piston chamber and whichswitches compressed gas flow to and from a piston chamber, the pneumaticvalve being configured as a main pneumatic valve assembly with slidablyreceived pneumatically sealed valve member being externally actuated bycompressed gas to change positions by compressed gas fluid pressure onone sealed chamber end of the valve member, compressed gas fluid flowbeing directed to switch gas flows to alternate position of the valvemember through fluid conducting ports and conduits from inward flowingto outward flowing and when gas fluid pressure is removed from onesealed chamber end of the valve member and gas fluid pressure is appliedto an opposite sealed chamber end of the valve member compressed gasfluid flow is directed to switch gas flows by alternating position ofthe valve member through fluid conducting port and conduit from outwardflowing to inward flowing.

In still yet another embodiment, the compressed gas switching pneumaticvalve assembly is comprised of both a pilot valve and a main valve gasfluid flow through the conduit from the fluid outlet of the pilot valveis used to actuate the compressed gas actuated main valve.

Referring now to FIGS. 20-21C yet another embodiment of the presentinvention illustrated.

Here a mechanical trigger and pneumatic trigger valve assembly andcompressed air conduit means is provided that can alter previouspneumatically powered pole saw systems as described herein such that amethod of operating is provided that forces the piston and blade to adefined limit position when in a static or “off” state. When themechanical trigger is pulled then linkage to the pneumatic trigger valveassembly repositions a slidably received shuttle which redirects variouscompressed air conduit means to function as if the trigger valveassembly were transparent to, or indistinguishable from previous conduitand valve operation and configuration means whereby reciprocation of thepiston and linked pole saw cutting blade occur.

Various embodiments of the trigger valve assembly when in the “on” stateare directed to U.S. patent application Ser. No. 13/448,340 filed Apr.16, 2012 wherein a pneumatically powered pole saw, comprising: anextendable pole; a head member secured to the extendable pole; a cuttingblade movably mounted to the head member; a piston linked to the cuttingblade, the piston being slidably received within a piston chamber; areciprocating main valve, the reciprocating main valve being configuredfor movement between a first position and a second position wherein thereciprocating main valve releases a portion of a source of compressedgas into the piston chamber on one side of the piston when thereciprocating main valve is in the first position causing the cuttingblade to move in a first cutting direction towards a limit of travel inthe first cutting direction and a first (pilot) check valve providesfluid communication to the piston chamber on another side of the pistoncausing the reciprocating valve to move from the first position towardsthe second position, when the cutting blade reaches the limit of travelin the first direction, the reciprocating main valve releases anotherportion of the source of compressed gas into the piston chamber on theanother side of the piston when the reciprocating valve is in the secondposition causing the cutting blade to move in a second cutting directionopposite to the first cutting direction and towards a limit of travel inthe second cutting direction and a second (pilot) check valve providesfluid communication to the piston chamber on the one side of the piston,the reciprocating valve moving from the second position towards thefirst position when the cutting blade reaches a limit of travel in thesecond direction.

The trigger valve assembly improves, in at least two significant ways,the pneumatic pole saw operation previously described in U.S. patentapplication Ser. No. 13/448,340 filed Apr. 16, 2012, the contents ofwhich are incorporated herein by reference thereto. The describedembodiment makes use of but is not limited to pilot valves axiallymounted and attached to each end of the piston cylinder, which pilotvalves are described in U.S. patent application Ser. No. 14/394/738,which is a National Phase of International Application No.PCT/US2013/036564, the contents each of which are incorporated herein byreference thereto.

The first improvement provided by the trigger valve assembly providesthe tool operator with a consistent, known, static or “off” state valveand piston configuration. In the pneumatically driven pole sawembodiment a trigger valve assembly assures that the cutting blade canbe positioned in a fully extended state when not “on”, that is, when thepiston, connecting rod and blade are not reciprocating. Having the bladefully extended in the static state aids the operator. When the pneumaticpole saw's blade is fully extended outside of its housing it is easierto see and position the blade on a tree limb.

The second improvement provided by the trigger valve assembly is theelimination of an occasional stall condition of the main valve assembly.A stall can occur as the result of an anomaly in valve dynamics when thesupply of compressed gas is turned off. The main valve can, when gaspressure drops, be left in a dysfunctional position. Then, when the mainvalve is in this dysfunctional state, and compressed gas pressure isturned back on, the reciprocating action of the main valve can no longeroccur and the pneumatic pole saw operation has stalled. With theinclusion of the trigger valve assembly this occasional stall conditionis eliminated. The simple action of releasing the hand operated triggerallows a spring to return the internal shuttle of the trigger valve tothe static state, which state allows compressed gas to resets the mainvalve to a known good position, thereby eliminating a possible stallcondition.

FIG. 20 shows mechanical trigger 440 connected by cable 441 to triggervalve shuttle 420 which is a component part of trigger valve assembly422. FIG. 20 also shows piston rod 433, piston cylinder 360 with pilotvalves 361 and 362 mounted on each end of piston 360. Axially mountedpilot valves 361 and 362 are also described in U.S. patent applicationSer. No. 14/394,738, which is a National Phase of InternationalApplication No. PCT/US2013/036564, the contents each of which areincorporated herein by reference thereto. A main valve 400 is alsoshown, however, conduits associated main valve assembly 400, pistoncylinder 360, pilot valves 361 and 362, and trigger valve assembly 422are not included in this FIG. 20 which shows only the outer views of theassemblies and does not show the internal components. Sectional views ofthe assemblies in FIG. 20 are shown in FIG. 21A and are the samesectional views as seen in FIGS. 21B and 21C wherein various internalcomponent states are shown along with the conduits (gas tubing)associated the pneumatic ports of the various assemblies. It beingunderstood that in at least one non-limiting embodiment, the pistoncylinder 360, pilot valves 361, 362, main valve assembly 400 and triggervalve assembly 422 may all be axially aligned in the pole or alignedwith the pole (e.g., exterior or interior) of the pole saw.Alternatively, only some of the aforementioned components (pistoncylinder 360, pilot valves 361, 362, main valve assembly 400 and triggervalve assembly 422) may be axially aligned in the pole or axiallyaligned with the pole of the pole saw. For example and in onenon-limiting embodiment, the piston cylinder 360, pilot valves 361, 362may be located within the pole of the pole saw while the main valveassembly 400 and trigger valve assembly 422 are located on an exteriorof the pole of the pole saw.

FIG. 21A is a cross sectional or cut-away view of FIG. 20, which viewallows observation of the various internal components of eachsubassembly. The actuator, piston cylinder 360 contains a piston 430which is sealed by O-ring 428 and connected to piston rod 433 which hasa seal, 429, on each end of piston chamber 360. The piston rod 433protrudes through the seals and through pilot valves, 361 and 362 ateach end. On one end of piston rod 433 there is a spring, 367, andspring stop, 368, and at the other end of piston rod 433 there is aspring, 445 and a spring stop, 446 and an attachment hole 444 which isused to attach a mechanical connecting rod 447 which transfers force tothe cutting blade as described in the referenced pneumatic pole sawpatent applications.

The piston and valve states observed in FIG. 21A are those of thepneumatic pole saw in static state, no motion, no cutting bladereciprocation. Cutting action of the pneumatic pole saw occurs asdescribed in the transitional dynamic state conditions of FIGS. 21B and21C. The manually operated trigger 440 is mounted on pin 439 whichallows trigger 440 to rotate on the pin and pull on cable 441 when forceis applied to the trigger. Cable 441 is connected to shuttle 420 whichis slidably received in trigger assembly 422 such that when cable 441pulls against shuttle 420 shuttle 420 can move toward trigger 440. InFIG. 21A there is no force applied to trigger 440 so spring 413, shownon the other end of shuttle 420, is pulling shuttle 420 toward itself,spring 413, until clip 419 attached to shuttle 420 contacts the housingof trigger valve assembly 422, stopping shuttle 420 from furthermovement under tension of spring 413. There are a number of ports on theouter surface of trigger assembly 422, including 408, 417 418, 409, 427,and 416. Some of these ports have fittings which provide connectionmeans for the air conduits (tubing). These conduits are 411, 410, 407,406 and 421.

One end of conduit 421 is connected to port 408 while the other end isconnected to symbol 438 (a circle with a dark dot in the center) whichis the American National Standards Association's symbol for a compressedair supply. In order to simplify FIGS. 21A, 21B and 21C this symbol isused in four locations to show that conduits 421, 398, 435, and 442 iseach connect to a supply of compressed air. In this exemplary pneumaticsystem these conduits connect to the same main source of compressed air.The main source of compressed air is not shown nor is the main valvethat is understood to turn the main source of compressed air on and offwhen not in operation or when a trigger valve assembly is not part of anembodiment.

There are O-rings associated with trigger shuttle 420. These are 423,424, 425 426, 414 and 415. Depending upon the position of the shuttlethe O-rings direct compressed air from one conduit on one side of valveassembly 422 to a conduit or vent one another side of assembly 422 bysealing off alternative flow paths. As shown in FIG. 21A, compressed airflowing through conduit 421 passes across the void around shuttle 420which is sealed by O-rings 423 and 424 and out through port 416 intoconduit 406 to main valve assembly 400 where it enters through port 405and the compressed gas delivered to port 405 presses against the surfaceof main valve shuttle 401 forcing it toward the opposite port 395. Mainvalve shuttle 401 is sealed by four O-rings which O-rings seal thesliding surfaces of shuttle 401. Motion of shuttle 401 toward port 395creates a pocket of compressed air sealed by O-ring 396 and the onlyflow path available for this compressed air is to flow out of port 395into conduit 407 and from there through port 427 of trigger valveassembly 422 and then vent to atmosphere through port 409. Once mainvalve shuttle 401 is in its forced static positioned, as shown, close toport 395, air sourced through conduit 398 flows through the main valveand out through port 394 into conduit 393 and into the main pistoncylinder through port 392, thereby providing air pressure against piston430. Piston 430 is thus forced to stay in this position until trigger440 is pulled to alter the position of trigger shuttle 420 to initiatethe changes which will be described by reference to FIG. 21B. Note thatwhen no force is applied to trigger 440 trigger shuttle 420 blocks theflow of compressed air from either of the pilot valves 361 or 362 whichare connected respectively by conduits 411 and 410. Air sourced to pilotvalve 362 by conduit 365 can flow through pilot valve shuttle 366 andout orifice 391 into conduit 410 because piston 430 is being forced awayfrom pilot valve 362 and spring stop 368, attached piston rod 433, iscompressing spring 367 which is forcing pilot shuttle 366 against itsreturn spring 434 (shown in FIG. 21B). However, even though compressedair does pass through pilot valve 362 it cannot affect the main valveposition because the compressed air available in conduit 410 is blockedby the state of trigger valve 422 from flowing to main valve 400. Also,air sourced through conduit 435 cannot flow through pilot valve 361because pilot valve spring 431 holds pilot valve shuttle 432 away frompiston rod seal 429 thereby allowing conduit 411, connected to port 437,to vent to atmosphere through port 443.

It should be noted that piston rod 433 connects to a connecting rod thatin turn connects in this pole saw embodiment to a cutting blade. Withpiston 430 sealed by O-ring 428 inside the chamber of cylinder 360 andwith a continual delivery of compressed air provided through conduit393, and when compressed air is being delivered from the source but withno manual force applied to trigger 440, piston rod 433 will continue toforce the connecting rod that connects to the cutting blade, forcing thecutting blade to remain fully extended, which is a desirable state.

Also, as shown in FIG. 21A main valve shuttle 401 is always forced intothe location shown when system air pressure is applied and trigger 440is left in its static state as determined by spring 413.

Previous to the invention of a trigger valve means for use with apneumatically powered pole saw it was possible, during heavy vibrationtransfer to shuttle valve 401 and/or changes in angle of shuttle 401relative to gravity and with simultaneous removal of system airpressure, to have shuttle 401 become positioned in a location that didnot allow compressed air, when later reapplied from conduit 398, to passthrough main valve 400. Compressed air could neither go through toconduit 393 nor to conduit 403, or, alternatively, pressure might applyequally to both conduits. In this main shuttle 401 location compressedair to piston 430 does is directed such that piston 430 will not move,it is in a stalled state and hence neither pilot valve 361 nor 362,which activate at end of travel of piston 430, can be actuated toinitiate reciprocation of main valve 400. The invention of the triggervalve assembly and associated conduit configuration remediates thispotential stall condition, the main valve will always be returned to aknown and desirable state when no force is applied to trigger 440.

FIG. 21B shows the state of various components within each of thesubassemblies when full travel bidirectional reciprocating movement ofpiston rod 433 is in operation. Transition into reciprocation mode ofoperation is started when force is initially applied to trigger 440connected to cable 441 which force pulls trigger shuttle 420 causingshuttle 420 to change location to that shown in FIG. 2B. Compressed airpreviously applied through conduit 421 no longer has a path to port 416of conduit 406 as O-ring seal 424 now seals off the previous air flow toconduit 406. Instead, conduit 406 now vents compressed air from port 416through the shuttle to port 417 and into conduit 411 connected to port437 of pilot valve 361 which provides a path to vent port 443. Theventing of compressed air in conduit 406, which connects through port405 to one side of main valve 400, allows shuttle 401 to move from itsposition shown in FIG. 2A to the position shown in FIG. 21B whencompressed air is supplied through conduit 407 to force main shuttle 401to move. Compressed air is delivered to conduit 407 when trigger shuttle420 is first moved to the position seen in FIG. 21B, which change inposition connects conduit 407 through port 415 to port 418 whichconnects to conduit 410. The initiation of shuttle 420 movement occurswhen pilot valve 362 is located as shown in FIG. 21A since piston 433 isstill initially forcing end cap 368 to compress spring 367 which hascontinued to force pilot valve shuttle 366 to the position shown in FIG.21A which provides a path for the source of compressed air deliveredthrough conduit 442 to flow across pilot valve shuttle 366 through port391 and into conduit 410. Upon initial movement of trigger shuttle 420to the position shown in FIG. 21B the compressed air contained in tube410 flows through conduit 407 to port 395 of main valve 400 and forcesshuttle 401 sealed by O-ring 396 to move to its location shown in FIG.21B. Movement of main valve shuttle 401 now provides a path for supplyair through conduit 398 to connect to port 402 and through conduit 403to piston cylinder 404 where it applies air pressure to piston 430connected to piston rod 433 which starts the motion of piston rod 433.Piston 430 continues to move away from pilot valve 361 and toward pilotvalve 362 as shown in FIG. 21B. Motion of piston 430 and attached pistonrod 433 continues in this direction until pilot valve 361, which isbeing held in its position shown in FIG. 21B by spring 431 which isinternal to pilot valve 361. Pilot valve 362 also contains a spring,434, which moves shuttle 366 in the position seen in FIG. 21B as soon aspiston rod 433 moves sufficiently to remove force applied by spring 367.

As shown in FIG. 21B, with both pilot valves 361 and 362 held in thevent positions shown by their respective internal springs 431 and 434,no pressure is applied to switch the state position of the main valveshuttle 401 until the piston rod 433 reaches end of travel. With thedirection of travel of piston 430 away from pilot valve 361 and towardpilot valve 362 piston 430 will continue moving until piston rod 433connected to piston 430 reaches end of travel as shown in FIG. 21C wherespring 445 is compressed against pilot valve shuttle 432. The motion ofpilot valve shuttle 432 opens up a flow path from a source of airthrough conduit 435 across shuttle 432 and through port 437 and intoconduit 411. Conduit 411 conducts the air flow through port 417 oftrigger valve assembly 422 to port 416 connected to conduit 406 to port405 of main valve 400. Conducted source air from tube 406 whose pressurebuild up was initiated by end of travel of piston rod 433 actuatingpilot valve 361 now forces main valve shuttle 401 to actuate to movefrom its position as shown in FIG. 21B to its opposite state position asshown in FIG. 21C. When this compressed air activated switching of themain valve occurs source air flowing through conduit 398 is redirectedfrom conduit 403 to conduit 393 and reverses the direction of piston 430which is now moving away from pilot valve 362 and toward pilot valve361. As the piston 430 approaches pilot valve 361 piston rod 433approaches its end of travel as shown in FIG. 21A. When pilot valve 362is moved by end stop 368 of FIG. 21A compressing spring 367 which inturn moves pilot valve shuttle 366 to open a flow path for the source ofcompressed air to flow through conduit 442 across shuttle 366 to port391 connected to conduit 410. Since the trigger 440 is still applyingforce to trigger shuttle 420 as seen in FIG. 21B which state conductscompressed gas from actuated pilot valve 362 through conduit 410 intoport 418 and through trigger valve 422 out port 427 and into conduit 407which delivers the compressed air to port 395 of main valve 400 to moveshuttle 401 away from port 395 and toward port 405. Moving shuttle 401switches the flow of compressed air from delivery to conduit 393 toconduit 403 as shown in FIG. 21B and the piston direction is againreversed.

As long as trigger 440, connected to trigger shuttle 420 is held byforce against the spring back pressure of spring 413, as seen in FIG.2B, the reciprocation motion which occurs when the piston rod reachesend of travel, activating a measure of compressed air through thedesired flow channel provided by the trigger shuttle 420 and into themain valve 400 to switch the flow of compressed air from one conduitconnected to an port one side of piston cylinder 360 to an port on theopposite side of the piston cylinder 360 then the reciprocation functionwill continue to move the piston and its attached piston rod in areciprocating motion.

Since, in this embodiment a connecting rod is attached to hole 444 ofpiston rod 433 as shown in FIG. 21C and the connecting rod is attachedto a cutting blade the cutting blade is reciprocated by force providedby the air supply and the piston cylinder in the described manner.

In one non-limiting embodiment, the trigger valve assembly has amanually activated trigger which, when activated by hand, alters theposition of a slidably received shuttle within said trigger valveassembly, thereby altering the interconnections of fluid conduits whichare connected between the trigger valve assembly and varioussubassemblies. While in the static state, that is, when no force isapplied by hand to the trigger, the trigger valve assembly providesfluid flow paths which direct compressed air through conduits whichforce a main valve assembly to a known static powered state whereincompressed gas is applied to one side only of a piston cylinder whichpiston cylinder is mechanically linked through connecting rod to acutting blade, resulting in the cutting blade to be forced to reside ina known static state when no force is applied to the trigger. When thetrigger is pulled, the trigger shuttle is moved, redirecting conduitconnections into paths that, in conjunction with a main flow valve,piston cylinder, and pilot valves, results in the reciprocating motionof the piston and linked rod which provide reciprocating action to therod coupled cutting blade.

FIG. 22 illustrates a pole saw 410 in accordance with one non-limitingembodiment of the present invention. FIG. 23 illustrates a portion ofthe pole saw illustrated in FIG. 22. FIGS. 24 and 25 illustrate atrigger 440 in accordance with one non-limiting embodiment of thepresent invention. FIG. 26 illustrates the main valve or main valveassembly 400 and the trigger valve assembly 422. FIGS. 27 and 28illustrate a limb stop 499 having a portion 501 configured to grasp andpull cut limbs downward.

While the invention has been described with reference to one or moreexemplary embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

What is claimed is:
 1. A pneumatic valve assembly with a trigger forswitching the pneumatic valve assembly between two or more valveoperation modes, the valve operational modes are determined by selectionof fluid conduits by a trigger valve assembly of the pneumatic valveassembly which interconnects fluid conduits to a main valve, pilotvalves and a pneumatic cylinder of a fluid powered pole saw and whereina piston located in the pneumatic cylinder is mechanically coupled to acutting blade of the pole saw and the trigger is operatively coupled tothe trigger valve assembly.
 2. The pneumatic valve assembly of claim 1,wherein valves of the trigger valve assembly are configured to provide astatic state, held to one extreme position of the piston wherein thecutting blade is held in a fully extended position with respect to thepole saw.
 3. The valve assembly of claim 2, wherein a third state of thetrigger valve assembly positions a piston rod operably coupling thepiston to the cutting blade in a static position that holds the pistonrod and the cutting blade in a fully retracted state with respect to thepole saw, the fully retracted state being completely opposite to that ofthe fully extended position.
 4. The valve assembly of claim 1, whereinthe piston is mechanically coupled to the cutting blade by a piston rod.5. The valve assembly as in claim 4, wherein the piston rod coupling thepiston to the cutting blade is a carbon fiber rod.
 6. The valve assemblyof claim 1, wherein the piston is mechanically coupled to the cuttingblade by a cable and a return spring.
 7. A method of manually triggeringa configuration of valves between pneumatic pilot valves and main valveswhich control the flow of compressed fluid to a pneumatic cylinder of apneumatically powered pole saw, the method comprising the steps of:actuating a trigger valve assembly via a trigger such that apneumatically driven blade of the pole saw is held in a fully extendedposition with respect to the pole saw when reciprocating motion of thepole saw piston is deactivated; and biasing a shuttle of the pole saw toa position corresponding to the fully extended position of the bladewhen the shuttle is not in the position when reciprocating motion of thepole saw piston is deactivated.
 8. A pneumatically powered pole sawcomprising: a pole; a cutting blade movably mounted to the pole; apiston slidably received within a piston chamber of the pole; a pistonrod coupling to the cutting blade to the piston; and a pneumatic valveassembly with a trigger for switching between two or more valveoperation modes, the valve operational modes are determined by selectionof fluid conduits by a trigger valve assembly which interconnects fluidconduits to a main valve, pilot valves and a pneumatic cylinder of thepole saw and wherein valves of the trigger valve assembly are configuredto provide a static state, held to one extreme position of the pistonwherein the cutting blade is held in a fully extended position withrespect to the pole saw.